Mylène Jansen

Clinical evidence and molecular mechanisms of KJD 193 10 unicompartmental knee OA. None of the studies provided a reasoning for their choices on the amount of distraction or the distraction duration. For the RCTs it was explained that the distraction time was shortened from 2 months to 6 weeks to decrease treatment burden. A separate published post-hoc analysis (insufficiently powered) demonstrated that there were no significant differences in outcome between patients treated with 6 weeks versus 2 months distraction, although the patients treated with 2 months distraction did show somewhat better results. 28,31 Each KJD study evaluated several different outcome parameters after KJD treatment, as shown in Table 1. These are summarized in the next sections, divided into patient-reported (clinical) outcomes and outcomes related to cartilaginous tissue repair. Patient-reported outcomes All studies evaluated patient-reported outcome measures (PROMs) before and after treatment, except for Abouheif et al, who only mentioned their patient had knee pain pre-treatment and was pain-free post-treatment. 19 All other studies statistically evaluated a change in pain, using a Visual Analogue Scale (VAS) of pain 14 , a four-point Likert scale for pain 15 , the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale 13,16,21–26 , and/or the Intermittent and Constant Osteoarthritis Pain (ICOAP) questionnaire. 24–26 For all pain parameters, as well as follow-up moments varying from three months to nine years (table 1), patients experienced significantly less pain after treatment compared to pre-treatment values. In fact, all symptom-related PROMs (walking capacity or stair climbing, the Japanese Osteoarthritis (JOA) knee score, or the WOMAC or Knee Injury and Osteoarthritis Outcome Score (KOOS) and all of their subscales, which evaluate stiffness, function, symptoms, sport, and quality of life) in all studies show a (statistically) significant improvement of around 40-60% at every time point between one and nine years after treatment. 13,14,32,15,16,19,22–26 Interestingly, it was shown that even patients who underwent a TKA several years after their KJD, still reported increased total WOMAC scores of on average 20 points before undergoing the TKA. 23 This increase is higher than the 15-point change considered the minimal clinically important difference and neared statistical significance ( p =0.067). 33 Apparently, other considerations besides the symptomatic complaints are important for patients to stay satisfied with their treatment (e.g. a relative worsening with the alternative option for TKA). Important to notice is that studies were retrospective, prospective cohorts, or small size RCTs. The quality of especially retrospective and prospective studies without a control group may provide bias, with clinical improvement comprising in part a placebo effect. Some studies also evaluated quality of life (EuroQol (EQ)-5D and Short Form (SF)-36 questionnaires). A statistically significant improvement in EQ-5D and in the physical components scale (PCS) of the SF-36 was observed. 24–26 The mental component scale (MCS)